Question

How many chlorine atoms are there in two calcium chloride formula units?

Answer 1

Answer Calcium chloride has the molecular formula $CaCl_{2}$  from which we can say that  one molecule of calcium chloride consist of one atom of calcium and two atoms of chlorine.

given : 2 mol of $CaCl_{2}$

total moles of chlorine atoms = number of atoms in one mole  × number of formula units= 2×2= 4

Total number of atom = Total number of moles × Avogadro number

So, total number of chlorine atoms =

             4 × 6.0221×$10^{23}$ =2.4088×$10^{24}$ atoms

Answer 2

Calcium chloride has the following formula: CaCl2
Based on this formula: one mole of calcium chloride contains two moles of chlorine

Therefore: two moles of calcium chloride would contain four moles of chlorine.

Number of atoms = number of moles x Avogadro's number
Number of atoms = 4 x 6.022 x 10^23 = 2.4088 x 10^24 atoms